Creating a Vetinari Clock Using Antique Analog Meters

Can you imagine a clock formed from old analog meters mounted in an antique-looking wooden box? Now imagine an interpretation of a Vetinari clock (the mind boggles).

As you may recall, the Mighty Hamster (a.k.a. Mike Field) graced my humble office with a visit a couple of weeks ago. (See All Hail the Mighty Hamster.) While he was here, Hamster noticed some of the antique analog meters scattered around my office, and he shared an idea with me -- to build a clock using this sort of meter as the display. Hamster kindly said that I was free to run with this idea myself, so I added it to my list of hobby projects. (See Juggling a Cornucopia of Projects.)

Most of the meters in my possession were already committed to other projects. Fortunately, at the time of Hamster's visit, the annual Huntsville Hamfest was fast approaching. In fact, the Hamfest took place this past weekend. It opened at 9:00 a.m., but I got there at 8:15 a.m., because I wanted to be at the front of the queue. I'll be posting a detailed blog about the Hamfest with lots and lots of pictures as soon as I get a spare moment.

All I can say is that I made off like a bandit on the antique meter front. When I attended last year's event, I arrived empty handed and ended up staggering around with loads of carrier bags. I soon noticed that the more experienced attendees were sporting backpacks to stash their acquisitions. This year, I wore a backpack, but I wish I'd taken a rolling trolley, because I had to make numerous trips back and forth to my truck. The image below shows the meters I picked up, along with a few other items I couldn't resist.

Yes, I know this is a lot of meters. What can I say? I am a weak man when it comes to antique stuff in general and analog meters in particular. All I know is that, when you can pick up meters like this for only $2 apiece, you grab them while the grabbing is good. Quite apart from anything else, I promised to pick up some meters for the Mighty Hamster. As soon as I post this column, I'll email him to ask which ones he wants.

I decided to use a large meter to display the hours and two medium-sized meters to display the minutes and seconds. I also plan on using a small meter to flip back and forth like a metronome in time with the "tick-tock" sound I intend to generate.

Max, this is going to be an awesome project - one where I think everybody will get the juxtaposition of old and new tech.

I still think that making it "dead on" accurate using a GPS time source would be pretty cool - "I'll just sync my pocket watch with atomic clocks orbiting the earth, using my steam-punk analogue meter clock".

Maybe make the seconds tick inconsistently, but have it bang-on when the seconds hand goes from full scale back to zero.

Neat project! I've lived more in the digital realm than the analog, so I'm curious how you're planning to drive these meters. Do you have the voltage and current specs for each? I imagine they'll require more power than a microcontroller output could provide so I'll have to stay tuned for the next report to learn how you plan to do that.

How about doing the whole thing analog? Each meter can be driven from a timebase like an oscilloscope or analog computer. You can sync between them the same way the horizontal and vertical waveforms are synced in an analog TV, but with more stages. And then sync the whole thing to 50/60 Hz line frequency to keep accurate time.

Yeah, parabolic. A-T is third-order. For both, cut angles can select the curve parms, making the field wonderfully complicated. I used to have a booklet from Fox with some details, but can't find it; things like using crystals in series to get compensation, DC bias effects, good stuff.

@ GSKrasle Could you build a PLL with the relay cycling as input, and take a multiplied output frequency?

Imagine how many hours that would take to lock. You have a VCO generating about a 1sec output that gets knocked down to 1 minute pulses to be compared to the signal from the relay. The phase error is then used to adjust the VCO frequency until the error is really small. You'd need lots of 1 minute pulses for the loop to do it's thing and sync the VCO to the relay.

Hamfest site is hamvention.org. Dates for 2015 are May 15-17. We are at the Quality Inn Suites. On Maxton Rd, is a solid mile of hotels and restaurants near the airport and convention center. Currently reserved for Fri-Sun but could modify easily. Joe and his wife (same schedule as us for now) likely not interested in the tour as they have been going since before they rename the Hamvention!

Another interesting property of the 32K tuning forks: their frequency vs. temperature curve is a parabols, with the peak right at 37C! Your wrist is the oven..... also explains why a (properly trimmed) watch will lose time when off your wrist.